Tissue microarrays are en route to becoming a very important technology in cancer research. Identification of markers that can be routinely used in diagnosis, prognosis, and therapeutics in cancer patients will follow from this high throughput technology. It also can provide a practical bridge between gene expression array technology and the clinical practice of pathology and oncology. As with other high-throughput technologies in medical research, tissue microarrays will require an intensive informatics infrastructure to achieve their potential. Standards are essential so that the clinical diagnostic and therapeutic information accumulated from different sources can be freely communicated and integrated. We propose here to create a series of Tissue Microarray Informatics Workshop in order to 1) provide a forum for informaticians, pathologists, and scientists using tissue microarrays to meet and discuss requirements for the informatics standards that are required to support this high throughput technology, including reporting of results, fabrication parameters, and imaging; and 2) provide an environment for the creation and ongoing participation of a working group to define and publicize these standards. The first workshop is designed to bring together informaticians involved in standards development and pathologists and scientists utilizing tissue microarrays in practice and research. It is this union that will lead to the definition of common data elements for reporting results from tissue microarrays. The ultimate objective for this first workshop will be the establishment of a working group to define common data elements for data records. The working group will be directed under the auspices of the Association of Pathology Informatics (API). The API will make the results available in the public domain to the pathology and scientific community. We anticipate that standards for imaging, fabrication, controlled vocabulary and ontologies, data analysis, and XML for tissue microarray data will be issues for this group to address in the future. Workshops will be help biennially in conjunction with two major pathology informatics symposia: the Automated Information Management in the Clinical Laboratory Meeting held in May at the University of Michigan and the Advancing Pathology; Informatics, Imaging and the Internet held in October in Pittsburgh. The API hold its meetings biennially at these symposia. Given the broad range of informatics topics required to provide an infrastructure for tissue microarray data reporting, we seek 5-year support for the workshops.